Fluid-based switches, such as liquid metal micro switches (LIMMS) have been made that use a liquid metal, such as mercury, as the switching element. The liquid metal may make and break electrical contacts. Alternately, a LIMMS may use an opaque liquid to open or block light paths. To change the state of the switch, a force is applied to the switching fluid, which causes it to change form and move.
Substrates used to manufacture the LIMMS may be held together with adhesives, such as polymers or thermoplastic perfluorocarbon material. The adhesives used may not withstand some assembly conditions (e.g., soldering temperatures). The adhesives may break down and release harmful products at elevated temperatures, which may occur during manufacturing or use. Elevated temperature cycles may inject harmful gases into the LIMMS channels, which may cause corrosion to liquid metal or the substrate. This corrosion may also create gas bubbles in the adhesive material, which may weaken the bond holding the channel plate to the substrate. The liquid metal may escape by vapor phase diffusion using the bubbles as a high permeability leak path through the adhesive material. If the liquid metal is mercury, this may cause negative environmental and health problems. Additionally, if a bubble-type leak path is present, environmental gases may rapidly diffuse into the interior of the switch and cause corrosion of the liquid metal or other internal structures.
Additionally, polymers may absorb gases and/or moisture and may outgas during use, which may cause chemical contamination of the interiors of the package. Polymers also do not seal hermetically, so additional sealing is required to create a hermetic switch.